Capacitive detection systems and methods

Abstract

The invention is related to capacitive detection systems and methods. In one embodiment, a capacitive detection system comprises a first transmitter electrode and a first receiver electrode disposed in a first seat and configured to form a first capacitor, and a second transmitter electrode disposed in a second seat and configured with the first receiver electrode to form a second capacitor.

1. A capacitive detection system comprising:
 a first transmitter electrode and a first receiver electrode disposed in a first seat and configured to form a first capacitor; 
 a second transmitter electrode disposed in a second seat and configured with the first receiver electrode to form a second capacitor; 
 a third transmitter electrode and a second receiver electrode disposed in a third seat and configured to form a third capacitor; 
 a fourth transmitter electrode disposed in the second seat and configured with the second receiver electrode to form a fourth capacitor; and 
 a fifth transmitter electrode disposed in the second seat and configured with the first receiver electrode to form a fifth capacitor and with the second receiver electrode to form a sixth capacitor. 
 
     
     
       2. The system of  claim 1 , further comprising a transmitter coupled to the second, fourth and fifth electrodes. 
     
     
       3. The system of  claim 2 , further comprising at least one buckle switch associated with the second seat and coupled to the transmitter. 
     
     
       4. The system of  claim 1 , further comprising:
 a first receiver unit coupled to the first receiver electrode; and 
 a second receiver unit coupled to the second receiver electrode. 
 
     
     
       5. The system of  claim 4 , further comprising an electronics control unit (ECU) coupled to the first and second receiver units. 
     
     
       6. The system of  claim 5 , wherein the ECU is coupled to the first and second receiver units by a bus. 
     
     
       7. The system of  claim 5 , wherein the ECU is adapted to determine a seat occupancy status of the first, second and third seats from data received from the first and second receiver units. 
     
     
       8. The system of  claim 1 , wherein a capacitance of the first capacitor varies according to an occupancy status of the first seat and a capacitance of the second capacitor varies according to an occupancy status of the second seat. 
     
     
       9. The system of  claim 1 , further comprising a first test electrode disposed in the second seat, wherein the first test electrode is arranged closer to the first receiver electrode than the second transmitter electrode is. 
     
     
       10. The system of  claim 1 , further comprising at least one additional electrode disposed in the first seat. 
     
     
       11. A vehicle seat occupancy detection system comprising:
 a first transmitter electrode capacitively coupled to a first receiver electrode, the first transmitter electrode and the first receiver electrode arranged in a first vehicle front seat; 
 a second transmitter electrode capacitively coupled to a second receiver electrode, the second transmitter electrode and the second receiver electrode arranged in a second vehicle front seat; 
 a third transmitter electrode capacitively coupled to the first receiver electrode and arranged in a vehicle backseat; 
 a fourth transmitter electrode capacitively coupled to the second receiver electrode and arranged in the vehicle backseat; and 
 a fifth transmitter electrode capacitively coupled to the first and second receiver electrodes and arranged in the vehicle backseat. 
 
     
     
       12. The system of  claim 11 , further comprising an electronics control unit (ECU) coupled to the first and second receiver electrodes and adapted to determine a seat occupancy status of the first and second vehicle front seats and the vehicle backseat based at least in part on a capacitive coupling pattern. 
     
     
       13. The system of  claim 12 , further comprising: at least one test electrode arranged in the vehicle backseat and capacitively coupled to one of the first or second receiver electrodes. 
     
     
       14. The system of  claim 11 , further comprising a backseat transmitter coupled to the third, fourth and fifth transmitter electrodes. 
     
     
       15. The system of  claim 14 , wherein the backseat transmitter uses a transmission technique selected from the group consisting of time division multiple access (TDMA), frequency division multiple access (FDMA), and code division multiple access (CDMA). 
     
     
       16. The system of  claim 14 , further comprising at least one seatbelt buckle switch associated with the vehicle backseat and coupled to the backseat transmitter. 
     
     
       17. The system of  claim 11 , further comprising at least one additional electrode disposed in at least one of the first or second vehicle front seats. 
     
     
       18. A method of determining an occupancy status comprising:
 sensing a first capacitance between a first electrode in a first seat and a second electrode in a second seat; 
 determining an occupancy status of at least a portion of the second seat based on the first capacitance; 
 sensing a second capacitance between a third electrode in a third seat and a fourth electrode in the second seat; 
 determining an occupancy status of at least a portion of the second seat based on the second capacitance; 
 sensing a third capacitance between a fifth electrode in the second seat and the first electrode; 
 sensing a fourth capacitance between the fifth electrode and the third electrode; and 
 determining an occupancy status of at least a portion of the second seat based on the third and fourth capacitances. 
 
     
     
       19. The method of  claim 18 , further comprising transmitting to the second, fourth and fifth electrodes using a transmission technique selected from the group consisting of time division multiple access (TDMA), frequency division multiple access (FDMA), and code division multiple access (CDMA).